Wood joint



Sept. 10, 1935. D RE 2,013,749

WOOD JOINT Filed Oct. 20, 1935 INVENTOR.

ATTORNEYJ;

Patented Sept. 10, 1935 UNITED STATES some @FFIQE 7 Claims. (Cl. 20-92)This invention relates to an improved mortiseand-tenon joint involvingmore particularly the use of an improved metal anchor which not onlyexpands the tenon within the mortise but also is forced into both tenonand mortise by the movement of inserting the tenon. No special formationor preparation is required either for mortise or tenon, and the anchoritself has the advantage of being simply and cheaply constructed andeasily positioned.

To the accomplishment of the foregoing and related ends said invention,then, consists of the means hereinafter fully described and particularlypointed out in the claims.

The annexed drawing and the following description set forth in detailcertain mechanism embodying the invention, such disclosed meansconstituting, however, but one of various mechanical forms in which theprinciple of the invention may be used.

In the accompanying drawing Fig. 1 is a transverse vertical sectionthrough a mortise, tenon and anchor, all parts being in the positionimmediately preparatory to assembly; Fig. 2 is a view corresponding toFig. l but showing the completed assembly; Fig. 3 is a larger scaleperspective View of the anchor; and Fig. 4 is a central vertical sectionthrough a modified form of anchor.

In making up the joint, a mortise I and tenon 2 are formed precisely asthough no anchor were to be used. The anchor 3 consists of a tubularmetal ferrule, the length of which may be varied according to thehardness of the wood and other features, but which in general will besomewhat longer than its diameter. Prongs 4, slightly flared, are formedon the bottom, and the top is preferably, although not necessarily,directed slightly inwardly, as at 5. The diameter of the circle in whichthe points of the prongs lie is just slightly less than the diameter ofthe mortise bottom, so that the anchor drops in easily and isself-centering. In the event that the mortise is of other shape thanround, the diameter of the prong point circle would be such as to beinscribable within the transverse section of the mortise.

In Fig. 4 a modification of the anchor is shown in which the top 6 isnot inwardly directed.

The joint is most readily constructed when the mortise opening isvertical. The anchor is dropped into the mortise opening, points down,as shown in Fig. l, and centers itself by reason of having a fairlylarge diameter relative to its height and having a spreading base. Thetenon is then forced down on the anchor into the position of Fig. 2,thus forcing the prongs i out and into the mortised member, and at thesame time completely seating the anchor in the bottom of the tenon. Therelative degree of penetration of the points 4 depends partly upon thehardness of the wood, both of mortised member and tenon and partly uponthe relative sharpness of the points and of the upper edge 5. Forexample, a tenon made of soft wood, for insertion in a mortised hardwood block may indicate the use of the form of anchor shown in Fig. 4rather than that shown in Fig. 3, so that the resistance between the topof the anchor and the tenon is great enough to force the prongs properlyinto the walls of the mortise.

The assembly of the joint, using this anchor, may be made either with orwithout glue, although it is contemplated that ordinarily glue will notbe necessary to the formation of a thoroughly tight and secure joint.The expansion of the tenon within the mortise due to the entering of theupper part of the anchor therein, and the intrusion and expansion of theteeth 4 into the wood below and beyond the bottom of the mortise combineto give out a powerful locking action. Where the upper edge of theanchor has a slight inward tendency, the engagement with the wood of thetenon is especially secure as at 7, due to an inward compressing effectupon the wood fibers. It will frequently be found however that theexpansion of the bottom of the tenon due to forcing the mass of theanchor thereinto is sufiicient, and consequently, where the character ofthe wood admits it, the straight-topped anchor shown in Fig. 4 issatisfactory.

It will be observed, particularly from Fig. 2, that the prongs 4, in thecompleted joint, extend only about half their length into the mortisedelement. The relatively wide angle of these points, best seen in Fig. 3,prevents any further penetration than is necessary to secure holding andthus avoids splitting the mortised element.

Although the usual application of this invention will be to a woodjoint, as indicated by the title and the foregoing description, and theferrule or anchor is to be made of metal in the ordinary instance, itwill of course be understood that the invention may be applied using anymaterials having physical characteristics which enables such use to bemade.

Other modes of applying the principle of my invention may be employedinstead of the one explained, change being made as regards the mechanismherein disclosed, provided the means stated by any of the followingclaims or the equivalent of such stated means be employed.

I therefore particularly point out and distinctly claim as my invention:

1. A mortise-and-tenon joint including an anchor element, said anchorelement comprising a hollow member with transverse ends, one of saidends being adapted to expand into the mortise walls and the other endbeing adapted to penetrate and expand the end of the tenon.

2. A mortise-and-tenon joint including an anchor having an open-endedhollow cylindrical body, thin edged, the lower end of said anchor beingexpanded transversely to the axis of the tube to a diameter slightlyless than the mortise diameter, whereby said anchor element will beself-centering in a mortise opening, the upper end being adapted topenetrate a tenon.

3. An anchor adapted for use in a mortise-andtenon joint comprising acylindrical tubular body inwardly directed at one end and serrated and.outwardly directed at the other end.

4. A mortise-and-tenon joint comprising in combination a tubular anchorhaving a spread end further expanded into the mortised material andhaving the anchor body centrally embedded in the tenon material withinthe depth of the mortise.

5. A mortise-and-tenon joint comprising in combination a unitary tubularanchor having one end expanded into the mortised material and having theanchor body embedded in and contracted upon part of the tenon material.

6. An anchor adapted for use in a mortiseand-tenon joint comprising ahollow cylindrical body and the wall sharp at each end, one end beingsplayed and the other inturned.

"1. An anchor adapted for use in a mortiseand-tenon joint comprising atubular body of stiff but thin material and a series ofoutwardlydirect'ed points around one end, said body being short and ofrelatively large diameter.

FRED A. DUNIVIIRE.

